1. Field of the Invention
The present invention relates to a winding apparatus providing steady tension and, more particularly, to a winding apparatus providing steady tension by dynamic adjustment of loading according to the shift velocity of a dancer roller.
2. Description of the Related Art
Generally, winding apparatuses have been broadly applied to industries of textile, printing, paper-making, rolling, and flexible electronics. Tension, of a sheet in process has to be steadily maintained in order to prevent undue extension or creases. However, in loading and winding processes, it is not easy to maintain steady tension of the sheet, since an outer radius of a loading roll releasing the raw sheet is continuously decreasing while an outer radius of a winding roll collecting the processed sheet is continuously increasing. Therefore, how to control the torque of the loading roll to steadily maintain the tension of the sheet between the loading and winding rolls and thus to prevent undesired situations in releasing or collecting the sheet has become an important issue in the development of winding apparatuses.
For example, a conventional winding apparatus trying to provide a sheet with steady tension is disclosed by Taiwan Patent No. M367182, titled as “Auto-tension-decreasing Device.” In operation of this conventional winding apparatus, necessary information about the sheet being processed, such as a total length, a thickness, and an initial tensional value, is necessary, so that rotational velocities of a loading roll and a winding roll can be controlled by a radius estimator and an auto-tension-controller to provide the sheet between the loading and winding rolls with steady tension. Besides, a tension detector is arranged between the loading roll and the winding roll to provide an actual tensional value of the sheet to the radius estimator as feedback. Thereby, the auto-tension-controller may adjust the rotational speeds of the rolls.
However, it is difficult to accurately measure the total length and thickness of the sheet, since the sheet is flexible and may have uneven thickness. An amount of calculating error will gradually increases as a total operation time increased if there is any error in the necessary information due to inaccurate measurement. Furthermore, the necessary information has to be updated once the material of the sheet is changed.
In light of this, it is desired to improve the conventional winding apparatus to simplify operation of the winding apparatus and to increase accuracy in tension control.